Tray stacking and unstacking apparatus

Abstract

An apparatus for stacking or unstacking trays comprising a tray holding mechanism and a drive member for moving the tray holding mechanism from an initial position along a prescribed closed path. In the stacking mode of operation, upon movement along the path, the tray holding mechanism moves downwardly depositing a first tray held thereby onto a second tray previously supplied to a receiving station on a tray support platform such as a conveyor. Continued movement along the path causes the tray holding mechanism to engage the second tray and to raise the stacked first and second trays to permit a third tray to be supplied to the receiving station by the conveyor. This sequence is continued until as many trays as desired are stacked. Alternatively, the disclosed apparatus may be switched to an unstacking mode wherein trays are deposited in succession from a stack to the receiving station on the conveyor.

I claim: 
     
       1. Tray stacking apparatus for use with supply means supplying a succession of trays to a receiving station in said tray stacking apparatus, said apparatus comprising: tray holding means for engaging and holding a tray supplied by the supply means, said tray holding means movable between a first position for engaging a tray and a second position for disengaging a tray;   moving means for reciprocally moving said tray holding means;   guide means for guiding a part of said tray holding means and defining a first and a second path along which said part of said tray holding means is sequentially moved by said moving means, movement of said part along said first path in one direction causing said tray holding means to deposit a first tray held thereby on a second tray supplied by said supply means to the receiving station, and movement of said part along said second path in the opposite direction causing said tray holding means to engage the second tray and to raise the stacked first and second trays thus allowing a third tray to be supplied to the receiving station by said supply means;   said first and second paths comprise first and second channels respectively, and said guide means includes pivotal levers at the junctions of said first and second channels for ensuring said part of said tray holding means moves along said first and second channels in proper sequence; and   said pivotal levers are movable between a first position for directing said part of said tray holding means along said first channel and then said second channel, and a second position for directing said part of said tray holding means along said second channel and then said first channel, thereby enabling said apparatus to be used as a tray stacking apparatus when said pivotal levers occupy said first position and as a tray unstacking apparatus when said pivotal levers occupy said second position.   
     
     
       2. Apparatus as claimed in claim 1 wherein said tray holding means comprises a pair of holding arms movable between a first position for engaging a tray and a second position for disengaging a tray, movement of said part along said first channel causing said holding arms to lower the first tray and to move to said second position for disengaging the first tray for stacking the first tray upon the second tray, and movement of said part along said second channel causing said holding arms to move to said first position for engaging the second tray, and continued movement along said second channel causing said holding arms to raise the second tray with the first tray stacked thereon. 
     
     
       3. Tray unstacking apparatus for use with conveying means for conveying the trays from a tray receiving station of said tray unstacking apparatus, said apparatus comprising: tray holding means for engaging a first tray and supporting a plurality of trays stacked on the first tray, said tray holding means movable between a first position for engaging a tray and a second position for disengaging a tray;   moving means for moving said tray holding means;   guide means for guiding a part of said tray holding means a defining a first and a second path along which said part of said tray holding means is moved by said moving means, movement of said part along said second path in one direction causing said holding means to lower the first tray onto the conveying means at said tray receiving station, and continued movement of said part along said second path causing said holding means to move to said second position for disengaging the first tray, movement of said part of said tray holding means along said first path in the opposite direction causing said holding means to move to said first position to engage a second tray stacked on the first tray, and continued movement of said part along said first path while said holding means are in said first position causing said holding means to raise the second tray from the first tray, thereby unstacking the first and second trays;   said first and second paths comprise first and second channels respectively, and said guide means include pivotal levers for ensuring said part of said tray holding means moves along said first and second channels in proper sequence; and   said pivotal levers are movable between a first position for directing said part of said tray holding means along said first channel and then said second channel, and a second position for directing said part of said tray holding means along said second channel and then said first channel, thereby enabling said apparatus to be used as a tray stacking apparatus when said pivotal levers occupy said first position and as a tray unstacking apparatus when said pivotal levers occupy said second position.   
     
     
       4. Apparatus as claimed in claim 3 wherein said tray holding means comprises a pair of holding arms movable between a first position for engaging a tray and a second position for disengaging a tray, movement of said part of said tray holding means along said second channel in one direction while said holding arms are in said first position causes said holding arms to lower the first tray to the receiving station, and continued movement of said part along said second channel in said one direction causes said holding arms to move to said second position for disengaging the first tray, movement of said part of said tray holding means along said first channel in the opposite direction causes said holding arms to move to said first position to engage the second tray, and continued movement of said part along said first channel in said opposite direction causes said holding arms while in said first position to raise the second tray from the first tray, thereby unstacking the first and second trays. 
     
     
       5. Tray stacking apparatus for use with supply means supplying a succession of trays to a receiving station in said tray stacking apparatus, said apparatus comprising: tray holding means for engaging and holding a tray supplied by the supply means, said tray holding means movable between a first position for engaging a tray and a second position for disengaging a tray;   moving means for reciprocally moving said tray holding means;   guide means for guiding a part of said tray holding means and defining a first and a second path along which said part of said tray holding means is sequentially moved by said moving means, movement of said part along said first path in one direction causing said tray holding means to deposit a first tray held thereby on a second tray supplied by said supply means to the receiving station, and movement of said part along said second path in the opposite direction causing said tray holding means to engage the second tray and to raise the stacked first and second trays thus allowing a third tray to be supplied to the receiving station by said supply means;   said first and second paths comprise first and second channels respectively, and said guide means include selector means at the junctions of said first and second channels for ensuring said part of said tray holding means moves along said first and second channels in proper sequence; and   said selector means are movable between a first position for directing said part of said tray holding means along said first channel and then said second channel, and a second position for directing said part of said tray holding means along said second channel and then said first channel, thereby enabling said apparatus to be used as a tray stacking apparatus when said selector means occupy said first position and as a tray unstacking apparatus when said selector means occupy said second position.   
     
     
       6. Tray unstacking apparatus for use with conveying means for conveying the trays from a tray receiving station of said tray unstacking apparatus, said apparatus comprising: tray holding means for engaging a first tray and supporting a plurality of trays stacked on the first tray, said tray holding means movable between a first position for engaging a tray and a second position for disengaging a tray;   moving means for moving said tray holding means;   guide means for guiding a part of said tray holding means and defining a first and a second path along which said part of said tray holding means is moved by said moving means, movement of said part along said second path in one direction causing said holding means to lower the first tray onto the conveying means at said tray receiving station, and continued movement of said part along said second path causing said holding means to move to said second position for disengaging the first tray, movement of said part of said tray holding means along said first path in the opposite direction causing said holding means to move to said first position to engage a second tray stacked on the first tray, and continued movement of said part along said first path while said holding means are in said first position causing said holding means to raise the second tray from the first tray, thereby unstacking the first and second trays;   said first and second paths comprise first and second channels respectively, and said guide means include selector means for ensuring said part of said tray holding means moves along said first and second channels in proper sequence; and   said selector means are movable between a first position for directing said part of said tray holding means along said first channel and then said second channel, and a second position for directing said part of said tray holding means along said second channel and then said first channel, thereby enabling said apparatus to be used as a tray stacking apparatus when said selector means occupy said first position and as a tray unstacking apparatus when said selector means occupy said second position.